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The thermophysical properties including density, heat capacity, thermal stability and phase behaviour of protic ionic liquids based on the N-methyl-2-hydroxyethylammonium cation, [C 2 OHC 1 NH 2 ] + , with the carboxylate anions (propionate, [C 2 COO]-, butyrate, [C 3 COO]-, and pentanoate, [C 4 COO]-) are reported and used to evaluate structure-property relationships. The density was measured over the temperature and pressure ranges, T = (298.15 to 358.15) K and p = (0.1 to 25) MPa, respectively, with an estimated uncertainty of ±0.5 kg⋅m-3. The pressure dependency of the density for these ionic liquids (ILs) is here presented for the first time and was correlated using the Goharshadi-Morsali-Abbaspour (GMA) equation of state, from which the isothermal compressibility, thermal expansivity, thermal pressure, and internal pressure were calculated. The experimental PVT data of the protic ILs were predicted by the methods of Gardas and Coutinho (GC), and Paduszyńki and Domańska (PD). The thermal stability was assessed by high resolution modulated thermogravimetric analysis within the range T = (303 to 873) K. The heat capacity was measured in the temperature range T = (286.15 to 335.15) K by modulated differential scanning calorimetry with an uncertainty in the range (1 to 5) J⋅K-1 ⋅mol-1. The Joback method for the prediction of ideal gas heat capacities was extended to the ILs and the corresponding states principle was employed to the subsequent calculation of liquid heat capacity based on critical properties predicted using the modified Lydersen-Joback-Reid method. The Valderrama's mass connectivity index method was also used for liquid heat capacity predictions. This series of N-methyl-2-hydroxyethylammonium was used to establish the effect of the anion alkyl chain length on the ionic liquid properties. Highlights ► pρT, measurements of N-methyl-2-hydroxyethylammonium carboxilate ionic liquids. ► Correlation of pρT data with Goharshadi-Morsali-Abbaspour EoS. ► Heat capacity by modulated differential scanning calorimetry. ► Thermal stability by high resolution modulated thermogravimetric analysis. ► Predictionof heat capacity by corresponding states and group contribution methods.

The cottonseed oil (CSO) extraction and processing areas including biodiesel (CSB) production created the need for density availability over wide ranges of temperature and pressure. In this work, densities of CSO and CSB were measured. The measurement of CSO density under pressure has never been reported in the literature. To address this limitation, this work reports new experimental data of densities of CSO measured at temperatures from 278 to 358 K and pressures from atmospheric up to 30 MPa using a vibrating tube densimeter. The measured densities of CSO were correlated with the Goharshadi−Morsali−Abbaspour equation of state (GMA EoS) with an absolute average relative deviation of 0.02%. The coefficients of GMA EoS for CSO and CSB were used to calculate the thermal expansivity and isothermal compressibility which influence power and fuel injection and they are rarely presented for vegetable oils and biodiesel, especially at high pressures. The group contribution method GCVOL, Halvorsen model, and Zong fragmentbased approach were used to evaluate the predictive abilities of CSO density data. Good predictions of oil densities were achieved with Halvorsen model for which absolute deviations are in the range of uncertainty of the measurements.

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